Annual performance factor calculation for funding (parameters and calculation tool)

I have found this

This is too big. What heating load does your house have?

I also believe so.
At 7°C AT 6.2Kw heating capacity. Would fit if you build according to the energy saving ordinance and have a HUGE house.
The question of the heating load is therefore justified, choose the heat pump accordingly!

The heating load is approximately 12 kW, 415 sqm to heat

I spoke to my heating engineer about the flow and return temperatures. He said that 30/23 degrees is not possible. That is not plausible and will not be accepted. In addition, the heat pump is supposed to be a split system, which is not good.

Is there already a room-specific heating load calculation?